Rotary connector switch



Sept. 15, 1953 M. E. GRIFFINS ROTARY CONNECTOR SWITCH Filed Nov. 26, 1949 So an" 6 mm 5 2 e MORRIS E. GRIFFINS 1N VEN TOR ATTORNEY Patented Sept. 15, 1953 UNITED STATES PATENT OFFICE ROTARY CONNECTOR SWITCH Morris E. Grifiins, Biverside,'Ill., assignor to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application November 26, 1949, Serial N 0. 129,599

141 Claims. 1

The present invention relates in general to automatic telephone systems, and its object, broadly stated, is to provide a new and improved circuit arrangement for the type of switches known as the rotary connectors.

Another object is to provide improved service facilities.

A feature of the present invention is the reduction in cost of this type of connector by requiring fewer relays and bank contacts by providing circuits such that certain relays perform functions which heretofore have been accomplished by single relays.

The foregoing objects and features together with others not specifically mentioned at this time will be further described in the detailed description of the operation of the connector switch taken in conjunction with the accompanying drawing, which shows a diagrammatic representation of the present invention in a single figure.

Briefly described, the present invention discloses a rotary connector switch providing for the establishment of connections to the first idle line of a group of private branch exchange lines or trunk lines which are allotted the same number in the telephone directory. The first digit of the three digit rotary connector operates the switch vertically. The second digit operates the switch in a rotary motion to a trunk in a group of trunks, and the first impulse of the third digit operates the busy relay to close the circuit to the rotary magnet so that the remaining pulses of the third digit operate the rotary magnet in case the busy relay is held energized by busy lines. When an idle line is reached, the busy relay releases to operate the switching relay, which in turn opens the rotary pulsing circuit and the connection is made to the idle line. The third digit can be any number up to the O and will depend upon the number of trunks in the group. The third, digit is assigned in accordance to the number of trunks in a group, for example 1 for a single trunk, digit 2 for two trunks etc. If all trunks in the group are busy, the busy tone is returned to the calling party when the connector comes to rest on the line representing the last line of the third digit dialled.

When it is desirable to dial a particular one of the trunk lines without the automatic rotary action, or when night service is desired, the first two digits select the desired line and the digit 1 is used as the third digit, since the first pulse is absorbed in the busy relay so that the rotary magnet does not step on the first pulse of the third digit. This circuit arrangement permits the use of a 300 point bank instead of the usual 400 point bank and reduces the number of relays required in this type of connector.

The accompanying drawing shows a three-digit combination rotary connector. The connector is of the well-known vertical and rotary Strowger type switch. Three hundred bank contacts are required for this connector; three contacts for each line, and are of the type well-known in the art. Substation A represents one of a plurality of subscribers and is connected to the connector by a line circuit I90, which is also well-known in the art.

The present invention having been described in general, will now be described in connection with the detailed description of the operation of the apparatus shown in the drawing.

Referring to the drawing, it will be assumed that a calling party desires to establish a connection to substation A, which is one of a plurality of substations accessible to the group of bank contacts designated first group in the upper right hand corner of the drawing.

In response to the establishment of a call from a calling subscriber over a preceding switch train, not shown, in a well-known manner, this connector is seized from the immediate preceded switch normally a selector circuit, in a well-known manner over the line conductors 93 and 94 and the control conductor 92.

With the connections established, line relayv I0 is operated over the calling line loop through conductors 93 and 94. The preceding switch train placing a ground connection on conductor 92. Relay l0 operated and contacts ll make to operate release relay 20. Simultaneously with the operation of relay l0, transfer relay 30 operated over the following path: conductor 92, V. O. N. contacts 3, relay 39 and battery. Contacts 34 make to prepare the circuit for the pulsing of vertical magnet l. Contacts 33 prepare a locking circuit for relay 30. Contacts 32 prepare the circuit for the operation of switching relay 69. Relay 20 operates and contacts 2| further prepare the circuit for stepping the vertical magnet l. Contacts 24 make to put ground on conductor 92, busying the connection from seizure from other calls during the time it is held by the calling party and holding the preceding switches in the train operated and busying them. Contacts 25 make to prepare locking circuits for busy and testing relay 50, ring cut-off relay l0, and switching relay 69. Contacts 23 open the circuit to the release magnet 5.

The connector is now prepared to receive the impulses transmitted as a result of the dialing of the first digit. Let us assume that the calling party dials 315. The circuit to line relay I is intermittently interrupted in response to the operation of the calling device, not shown, by the calling subscriber. The intermittent operation of relay I0 pulses the vertical magnet over the following path: ground, back contacts I2, contacts 2|, contacts 66, contacts 34, contacts 58, vertical magnet I and battery. After the first vertical step, V. O. N. spring contacts 3 break to open the initial operating circuit of transfer relay 30 and contacts 2 prepare the circuit to release magnet 5'. Relay 3!] being slow-to-release. relay remains operated until the completion of the first series of impulses dialled by the first digit over the following path: ground, contacts I2, contacts 2 I, contacts 66, contacts 34, relay and battery.

The wipers 6, I, 8, and 9 are now resting opposite the third level of bank contacts. Relay 3|! releases after an interval and contacts prepare the circuit for pulsing the rotary magn t; contacts 3| prepare the. locking circuits for ring cut-oif relay Ill and relay 5'9, and contacts 32 open the operating circuit to switching relay 60. The connector is. now prepared for the dialing of the second digit. The calling subscriber now manipulates the calling device, not. shown, in accordance with the second digit of the directory number. The circuit to the line relay I0 is intermittently interrupted to pulse the rotary magnet 4 over the following path: ground, back contacts I2, contacts 2|, contacts 66, contacts 35, contacts 43,. armature I8, contacts 56, relay 40,, rotary magnet 4, and battery.

The operation of the rotary magnet 4 steps the wipers into engagement with the bank contact corresponding to the second dialled digit, or in thisexample the first bank contact in the third level. Series relay operates and contacts 42 make before contacts 43 break. After the first rotary step, the remaining pulses of the second digit, if more than the digit one, will operate the rotary magnet 4 over the following path: ground, back contacts I2, contacts 2|, contacts 66,, contacts 35, contacts 42, relay 40, rotary magnet 4 and battery. The wipers 6, I, 8 and 9 are now resting on the first bank contact of the first group.

When the series relay 4Il operated, contacts 4| make to operate the ring cut-off relay I0. Relay 40 releases after the completion of the dialing of the second series of pulses. Ring cut-off relay I0 operated and contacts I2 grounds the supervisory lead. 9|; contacts I3 prepare a connection from the line conductor 93 to wiper 6. Contacts T6 complete a locking circuitfor relay I0 and contacts 1! prepares a circuit for operating relay 30. Armature I8prepares theoperating circuit for busy and test relay over the following path: battery, relay 5|), armature I8, contacts 4-3, contacts 35, contacts 66, contacts 22I, contacts I2 and ground. Relay 4|] releases and contacts 4| remove ground from the operating circuit of relay 10. The calling subscriber now dials his third digit which is 5. Let us assume at this time that the first trunk line in this group terminating; in bank contact 20I is idle. The first pulse of the third digit interrupts the line relay Ill and the busy and test relay 50 absorbs the first pulse and operates over the following path: ground, contacts I2, contacts 2|, contacts 66, contacts 35, contacts 43, armature I8, relay 5|] and battery. Relay 50 operates and contacts 5| prepare a busy tone conductor 93 to the subscriber's line.

circuit to conductor 93; contacts 54 complete a locking circuit for relay 50; contacts 52 complete a testing circuit from bank contact 20| and wipers I and 8 to relay 50; contacts prepare an operating circuit for relay 30; contacts 56 open the circuit to the series relay 40 and the rotary magnet, and contacts 5! prepare another circuit to the rotary magnet.

After the first pulse of the third digit line relay |0 reenergizes and at contacts completes the circuit for operating relay 30 as follows: from ground contacts I I, 55, IT to the uper winding of relay 30 to battery. Relay 30 operates and contacts 3| open the locking circuits of relays 50 and III to release relay I0; contacts 33 complete. a locking circuit for relay 30 and contacts 34 prepare the rotary stepping circuit. Upon wipers I and '8 finding an idle line, busy relay 5D releases. Since the connector is a battery searching connector, the contact 20| when idle will have a battery potential which will be effective to release relay 50. Relay 50 releases and contacts 5| open the circuit to busy tone conductor 98.; contacts 53 complete the circuit to operate switching relay contacts 55 remove the ground connection from contacts II to release relay 30.

Relay 60 operates over the following path; battery on contact 20I, wiper I and 8, contacts 53,, relay 60., contacts 32, contacts 25, and ground. Contacts 6| start the ringing machine over an obvious circuit. Contacts 62 send a ring back tone over the following path to the calling party: conductor 9I,v C3, contacts 82, contact I5, CI and Contacts 63 and 61, prepare thev ringing circuit to the called subscriber's line. Contacts 65 complete a locking circuit for relay 60. Contacts 64 operate B. C. O. relay, not shown, in the line circuit IOIJ. and guards the called line from intrusion in a well-known manner.

At contacts 66 relay 60 opens the pulsing circuit to rotar magnet 4 so that the remaining impulses of the third digit are ineffective to operate the switch. Therefore, in case the first trunk line in the called group is idle the connector switches through and the remaining impulses of the third digit are absorbed.

The operation of switching relay 60 at contacts 63 and 61 completed the circuit for ringing the called subscriber, such as A, as follows: from battery connected interrupted generator, upper winding of ring cut-off relay I0, contacts I4 and 63, wiper 6, bank contact IOI over the talking conductors in the line circuit I00 to called line A back to bank contact 30I, wiper 9, and contacts 61 and I9 to ground.

Relay 10 operates over the following path when the called subscriber removes his handset to answer the call: battery connected interrupted generator, relay I0, contacts I4, contacts 63, wiper 6, contact IDI, line circuit I00, the called line loop, contact 3', wiper 9, contacts 61 and ground on contacts I9. Contacts I3 and I9 make to prepare the talking circuit from the calling subscriber to the called subscriber A. Contacts I5 break removing ring back tone. Contacts I6 completes a locking circuit for relay 10 over the following path: battery, relay 10, contacts 16, contacts 3|, contacts 25 and ground.

Back bridge relay operates over the following path: battery, relay 80., contacts 73, contacts 63, wiper 6, contact IllI, over the talking, circuit through the line circuit and called line, contact 301, wiper 8, contact 6?, armature I9, relay 80 and ground. Contacts 85 and 88 make before contacts =84 and 8'! break to'reverse the polarity operation of relay 5U. The remainin pulses were ineffectual for stepping rotary magnet 4 since relay 58 released if the wipers 7 and 8 were on an idle line. The releasing of relay 5|] operated relay 60 which opened the pulsing circuit to the rotary magnet 4 at contacts 66.

Let us assume now that as digit 5 is dialled for the third digit,and that I and 8 wipers encounter a busy connection on the first bank contact of the called group. Therefore ground will be found on contact 20!. The first pulse will operate relay 50 in a manner previously described. When relay 5!) operated, the same circuit connections are in effect as were previously described with the exception that relay 50 is locked to the busy contact 20! and relay 60 does not operate. Relay 30 operates over the following path when line relay energizes after the termination of the first pulse: ground, contact ll, contacts 55, contacts 11, upper Winding of relay 30 and battery. Contacts 3| break to open the locking circuits for relays 50 and 1G. Contacts 33 complete a locking circuit for relay 30 until relay releases. Since the trunk line is busy, wipers I and 8 encounter a ground connectionon contact and therefore the relay 5|] will remain operated. Relay 'Hl released upon the breaking of contacts 3!.

The second pulse of the third digit now operates rotary magnet 4 which steps the wipers to the second contact of the firstgrou of contacts over the following path: ground, contacts l2, contacts 2|, contacts 66, contacts 34, contacts 51, rotary magnet 4 and battery. Relay due to its slow to release characteristics remains operated after release of relay 10 over the pulsing circuit. A similar operationcontinueswith each pulse until an idle line is found or until the termination of a series of pulses'controlled by the third digit. Let us assume further that all lines in the called group are busy and wipers 6, l, 8

and 9 now come to rest on the 5th contact of the trunk group. I

With the fifth contact busy, relay 50 is operated. Relay 30, the slow-to-release relay, remains operated until the third series of pulses terminate. When relay 39 operates, relay 10 releases and busy tone is transmitted to the calling party. If the fifth contact is idle or any contact preceding the fifth contact is idle, the relay 5!! releases in a manner similar to that previously described when contact 285 was idle and the call is switched through and the called subscriber is rung.

When the called subscriber is connected to the calling subscriber in a manner described for the first idle trunk line, and the parties have finished conversing, the calling party releases his handset and relay it releases over a path previously described for operating the same. Contacts ll break and relay 20 releases. Contacts25 remove ground from one of the locking circuit of relays and Ill; contacts 24 remove ground from conductor 92 to release the preceding switch-train contacts 23 prepare the circuit to the release magnet 5, and contacts 2| open the pulsing circuit. Relays 5i) and 10 however are maintained looked from ground at contacts '12 over contacts 82 until the called subscriber replaces his receiver.

When the called subscriber replaces his handset relay releases. Relay 80 releases and contacts 82 break thereby releasing relays 60 and 10 over a path previously described for locking the same. Contacts 83 complete the circuit for the operation of release magnet 5 over the following path: release ground conductor, contacts 83, contacts 23, V. O. N. contacts 2, release magnet 5 and battery. Release magnet 5 releases the connector which at off-normal contacts 2 opens the release magnet circuit irra manner well-known in the art.

Relay BB releases and contacts 6! open the ring machine circuit; contacts 63 and 67 open the talking circuit; contacts 64 remove a ground connection from 2D! to remove the busy marking from the line of subscriber A and to release the B. C. O. relay in line circuit H30; and contacts 66 again prepares the pulsing circuits. Relay l0 releases and the system is now prepared for future operation.

When calls are made to individual lines, the first digit dialled corresponds to the level in which the called line is located, the second digit corresponds to the terminal bank contacts in which the called line terminates, and the third digit dialled is digit one to operate the busy relay for the purposes of testing the engaged line.

In the instances where night calls or direct calls are desired, that is where a particular line of a group of lines is desired, the bank terminal number of the desired line is dialled for the second digit and the digit 17' is used as the third digit, and the operation is similar in all respects as was described for calling an individual line.

In case any idle trunk line in the second group of trunks, shown terminating in the 6th, 7th and 8th bank contacts in the 3rd level in the upper right hand corner of the drawing, is desired, the first digit dialled is digit 3 to operate the switch wipers vertically to the third level, the second digit dialled is digit 6 to rotate the wipers to the 6th bank contact in the third level, and the third digit dialled is digit 3 to cause the wipers to rotate to the 8th bank contact in the case the 6th and 7th test contacts are grounded (due to these linesbeing. busy) in a manner similar to that described for the first trunk group.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various changes will be made therein, and it is contemplated in the apparent claims, to cover all such changes as fall within the true spirit and scope of the invention.

. What is claimed is:

1. In a telephone system, an automatic switch having wipers and means for receiving a series of impulses, a magnet for rotating said wipers, a line relay in the switch operated by said series of impulses, a circuit for said magnet, a series relay connected in series in said circuit, means to control said circuit to cause the operation of said series relay and the operation of said magnet to rotate the wipers, means whereby said last means is controlled by the operation of said li e relay when operate by s id se es of impulses, a ring cu -01f r la a cir i o p lyi-ng ringing current to a called line, means whereby said last mentioned circuit is controlled by the operation of said ring cut-off relay, means for completing the circuit of said ring cut-off relay to disable the ringing circuit controlled thereby, means whereby said last means is controlled by the operation of said series relay when operated by said impulses.

2, In an automatic switch, a circuit over which the switch may be seized and over which a plurality of series of digital impulses are received, a line relay in said circuit, a circuit in.--

cluding a, release relay, said line relay intermittently operated in response to the receipt of said series of impulses, means for closing said release relay circuit, means whereby said last means is controlled by the operation of said line relay in response to the receipt of an impulse to operate said release relay, transfer relay, means for operating said transfer relay when said switch is seized, means for maintaining and releasing said transfer relay, means whereby said last means is also controlled by the operation of said line relay, a primary and a secondary operating means in the switch, means for actuating said primary operating means to step said switch in a primary movement, means whereby said last means is operated by the operation of said line relay in response to a first received series of impulses, means for transferring the control of said line relay from the primary operating means to said secondary operating means, means whereby said last means is controlled by the release trolled by said operation of the release relay and y the release of said transfer relay, a series relay, means for operating and releasing said series ay, means h e y sa la t mean i conl d b h o e at i sa d line relay when operated in respons o e rec ip of the se ond series of impulses, a ring cut-off relay, means lfor operating said ring cut-off relay, means whereby said last means is controlled by the operation of said series relay, means for further pr pa g t ci ui o aid e t relay, me ns whereby said last means ,is controlled by the operation of said ring cut-off relay and the re-, lease of said series relay, means for completing the circuit to said test relay, means whereby said last means is controlled by the line relay when operated in response to the receipt of a first pulse of a subsequent series of received impulses, means for connecting said secondary operating means to said line relay, means whereby said last means is controlled by the test relay operated in response to the completion of said circuit, the 'last means to again operate said secondary operating means to further operate said switch in a secondary movement, means whereby said last means is controlled by said line relay operated in response to the receipt of ,suct eeding impulses of said subsequent series of impulses.

3. In an automatic switch, a circuit over which the switch may be siezed and over whioh a plusrality of series of digital impulses are received, a

plu al o bank con ac s ar an d in levels and ups, a d on a ts w dle ha in one potential connected thereto and when busy having a difierent potential connected thereto, a. te t ,relay, an operating circuit for said test relay, a test circuit including a wiper for connecting said test relay to said bank contact, means in said switch for receiving a plurality of vS ries of digital impulses, means for stepping said wiper to desired level of contacts and for preparing said operating circuit, means whereby said last means is operated in response to receipt of impulses of the first digit, other means for stepping said switch to the first contact of a desired group, means whereby said last means is operated in response to the receipt of impulses of the second digit, means for completing said operating circult of said test relay to cause operation of said test relay, means whereby said last means is operated in response to receipt of the first impulse of a subsequent digit, means to complete said test circuit, means whereby said last means is controlled by the operation of said test relay, said test circuit energized to maintain said test relay operated if said first contact is connected to a busy potential, said circuit remaining um.- energized if said contact is connected to an idle potential, means for operating said other means to step said wiper onto the next bank contacts of said group of contacts until an idle line is found and means whereby said last means is controlled by said operation of said test relay.

,4. In an automatic switch, a circuit over which the switch may be seized and over which a plurality of series of digital impulses are received, a plurality of bankcontacts arranged in levels and in groups therein, said contacts when idle having one potential connected thereto and when busy having a different potential connected thereto, a test relay, a test wiper for connecting test relay to any of said contacts, means for stepping said wiper to select a level of said bank contacts, means whereby said last means is operated in response to the receipt of the first series of received digital impulses, a second means for stepping said wiper to select the first contact of said group of contacts, means whereby said last means is operated in response to the receipt of the second series of received digital impulses, an operating circuit for said test relay, a series relay, means for operating and releasing said series relay, means whereby said last means is operated by said second series of received impulses, means for preparing said test relay operating circuit, means whereby said last means is controlled by the operation of said series relay, other means for further preparing said test relay operating circuit, said other means controlled by the release of said series relay, means for completing said test relay operating circuit and operating said test relay, means whereby said last means is operated in response to the receipt of the first impulse of a third series of received digital impulses, means for completing another circuit for said test relay to maintain said test relay operated if said wiper is resting upon a contact having a busy potential connected thereto and for releasing said relay in case said wiper is resting upon a contact having an idle potential connected thereto, said last means controlled by the operation of said test relay, means including said second means for stepping said wiper to successive bank contacts, and means whereby said last means is operated by the remaining impulses of said third series of received digital 2 impulses during the maintained operation of said test relay.

5. In an automatic switch, a plurality of bank contacts arranged in levels and in groups, said contacts when idle having one potential connected thereto and when busy having a different potential connected thereto, a test relay, a test circuit including a wiper for connecting said test relay to said bank contacts, a circuit over which said switch is seized and over which impulses corresponding to a plurality of digits are received for operating said switch, a primary and a secondary operating means in said switch, control means in said switch operated in response to said received impulses, a transfer relay, means for operating said transfer relay, means whereby said last means is operated in response to the seizure of said switch, means for causing said control means to have control over said primary operating means, means whereby said last means is controlled by the operation of said transfer relay, means for operating said primary operating means to direct said wiper onto a level of said bank contacts, means whereby said last means is actuated by said control means when operated by the first series of received impulses, means to release said transfer relay, means whereby said last means is operated by said control means in response to the termination of the first series of impulses and also after the operation of said primary operating means, means for transferring the control of said control means from the operation of said primary operating means to the operation of said secondary operating means, said last means controlled by the release of said transfer relay, a series relay, means to operate said secondary operating means to direct said wiper onto the first bank contact of a group of said bank contacts and for operating said series relay, means whereby said last means is operated by said control means when thereafter actuated by' the second series of received impulses, means for releasing said series relay, means whereby said last means is operated by said control means when operated'in response to the termination of said second series of received impulses, a ring cut-off relay, means for operating said ring cut-off relay, means whereby said last means is controlled by the operation of said series relay, an operating circuit for said test relay, means for initially preparing said test relay operating circuit, means whereby said last means is controlled by the operation of said ring cut-off relay, other means for further preparing said test relay operating circuit, means whereby said other means is controlled by the release of said series relay, means to complete said test relay operating circuit to cause operation of said test relay, means whereby said last means is operated by the first impulse of a second series of received impulses, means for transferring the control of said control means from the operation ofsaid test relay to the re-operation of said secondary operating means, means whereby said last means is operated by said test relay, means for controlling said secondary operating means to step said wiper 'onto the next bank contact in case said test relayremains operated, means whereby the last mentioned means is controlled by the control'means when operated in response to the remaining impulses of said third series of impulses, other means for completing said test circuit for maintaining said test relay operated if said wiper is resting upon a busy contact and for releasing said test relay if said wiper i0 is resting upon an idle bank contact, means whereby said other means is controlled by operation of said test relay, means for disabling the control of said control means over the said secondary operating means and consequent further operation of saidsecondary operating means in response to the remaining impulses of said third seriesof impulses, means whereby the said last means is controlled by the release of said test relay.

6. In an automatic switch, a circuit over which the switch may be seized and over which a plurality of series of digital impulses are received, a plurality of test bank contacts arranged in levels and in groups, a testrelay, a test circuit including a wiper for connecting said test relay to said bank contacts, a first means for stepping said wiper to select a level of said bank contacts, a second means for stepping said wiper to select a contact in said group of contacts, a test relay, means for operating said first stepping means, means whereby said last means is operated in response to the first series of digital impulses, means for operating said second stepping means, meanswhereby said last means is operated in response to the receipt of the second series of impulses, means for operating said test relay, means whereby said last means is operated by the first impulse of subsequent series of impulses, means for completing said test circuit, and means whereby said last means is controlled by the operation of said test relay.

7. In an automatic switch, a circuit over which the switch may be seized and over which a plurality of series of digital impulses ar received, a plurality of test bank contacts arranged in levels and in groups, said contacts when idle having one potential connected thereto and whenbusy having a different potential connected thereto, a test relay, a test circuit including a wiper for connecting said test relay to said contacts, means for stepping said wiper to select a level of said bank contacts, means whereby said last means is operated in response to the first series of received digital impulses, a second means for stepping said wiper to select a contact of said'g'roups of contacts, means whereby said last means is operated in response to the second series of received digital impulses, an operating circuit for said test relay, a series relay, means for operating said series relay, means whereby said last means is operated in response to the receipt'of said second series of received impulses, means for initially preparing said test relayop crating circuit, means whereby said last means is controlled by the operation of said series relay, other means for further preparing said test relay operating circuit, means whereby said last means is operated in response to completion of said second series of received impulses, means for completing said test relay operating circuit andj',

for causing the operation of said test relay, means whereby said last means is operated by the first impulse of the third series of impulses, means contacts arranged in levels and in groups said' contacts when idle having onepotenti aLcd'n- 11 nected thereto and when busy having a different potential connected thereto, atest relay, a test circuit including a wiper for connecting said test relay to said bank contacts, a circuit over which said switch is seized and over which impulses corresponding to aplurality of digits are received for operating said switch, a primary and a secondary Operating means in said switch, a control means in said. switch operatedby said received impulses, a transfer relay, means to operate said transfer relay, means whereby said last means is controlled by the seizure of said switch, transfer means for causing said control means to have control over said primary operating means, means whereby said transfer means is controlled by the operation of said transfer relay, means for operating said primary operating means to direct said wiper onto a digitally selected level of said bank contacts, means whereby said last means is operated by said control means when actuated by the first series of received impulses, means for releasing said transfer relay, means whereby said last mentioned means is controlled by the primary operation of said switch upon the termination of said first tuation of said control means when operated by the second series of received impulses, an operating circuit for said test relay, a series relay, means for operating said series relay, means whereby said last means is operated by said control means when operated by said second series of received impulses, a ring cut-off relay, means for operating said ring cut-off relay, means whereby said last means is controlled by the operation of said series relay, means for preparing said test relay operating circuit, means whereby said last means is controlled by the release of said'series. relay and the operation of said ring cut-ofi relay, means for completing said test relay operating circuit to cause operati'onv of said test relay, means whereby said last means is actuated by the first impulse of the third series of received impulses, means for completing said test circuit to maintain said test relay operated if said wiper is resting upon a busy bank contact and for releasing said test relay if said wiper is resting upon an idle bank contact, and means whereby said last means is controlled by the operation of said test relay.

9. In an automatic switch, a plurality of bank contacts arranged in levels and in groups, said contacts when idle having one potential connected thereto and when busy having a different potential connected thereto, a test relay, a test circuit including a wiper for connecting said test relay to saidbank contact, a circuit over which said switch is seized and over which impulses corresponding to a plurality of digits are received for operating said switch, a series relay, means for stepping said wiper to select a level of contacts, means whereby said last means is operated by the first series of received digital impulses, other means for operating said series relay and for stepping said wipers to select the first contact of said groups of contacts, means whereby said other means is operated by the second series of received digital impulses, an operating circuit for said test relay, means for releasing said series relay, means whereby said last means is operated in response to termination of said second series of impulses, means for preparing said operating circuit, means whereby said last means is op-' erated by the release of said series relay after the completion of the selection of said first contact of said group of contacts, means for completing said. operating circuit to cause the operation of said test relay, means whereby said last means is operated in response to the receipt-of the first impulse of the third series of received impulses, means for completing saidtest circuit to maintain said test relay operated if said wiper is resting upon a contact having a busy potential connected thereto and for releasing said test relay if said wiper is resting upon a contact having an idle potential connected thereto, means whereby said last means is controlled by the operation of said test relay, means whereby said other means is operated by the remaining impulses of said third series of impulses and controlled by said test relay remaining operated for stepping said wiper onto the next bank contact of said group of contacts in search of an idle bank contact, a switching-relay, means for operating said switching relay, means whereby. said last means is controlled by the release of saidtest relay, means for disablingv said other means to prevent further stepping of saidwiper, and means whereby said last means is controlled by the operation of said switching relay,

1 0. In an automatic switch, a circuit over which the switch is seizedandover which a plurality of series of digital impulses are received, a plurality of bank contacts arranged in levels and in groups therein, said contacts when idle having one potential connected thereto and when busy having a different potential connected thereto, a test relay, a test circuit including. a wiper for connecting said test relay to said bank contact, means for stepping said wiper to select alevel of said bank contacts, means whereby said last means is-operated by the first series of received digital impulses, a second means for stepping said wiper to select the first contact of saidgroup of contacts, means whereby said last means is operated by the second series of received digital impulses, an operating circuit for said test relay, a series relay, means for operating said series relay, means whereby said last means operated bythe secondv series of received impulses,- means for preparing said test relay operatingcircuit, means whereby said last means is controlled by the operation of saidseries relay, other means for further preparing. said test relay operating circuit, means whereby said other means is controlled by the release of said series relay, means for completing said test relay operating circuit for operating said test relay, means whereby said last means is operated by the first impulse of the third series of received digital impulses, means for completing said test circuit for said: test relay to maintain said test relay operated it said wiper said third series of receiveddigitalimpulses and controlled by said test relay remaining operated, a switching relay, means for operating said switching relay, means whereby said last means is controlled by the release of saidtest relay, means for maintaining said switching relay operated independent of further operation of said test relay and independent of the connection to the potential on said bank contact, means whereby said last mentioned means is controlled'by the operation of said switching relay, means for disabling said second means to prevent further stepping of said wiper, and means whereby said last means is controlled by the operation of said switching relay.

11. In an automatic switch, a plurality of bank contacts arranged in levels and in groups, said contacts when idle having one potential connected thereto and when busy having a different potential connected thereto, a test relay, a test circuit including a wiper for connecting said test relay to said bank contacts, a circuit over which said switch is seized and over which impulses corresponding to a plurality of digits are received for operating said switch, a primary and a secondary operating means in said switch, control means in said switch actuated by said received impulses, a transfer relay, means for operating said transfer relay, means whereby said last means is controlled by the seizure of said switch, means for causing said control means to have control over said primary operating means, means whereby said last means is controlled by the operation of said transfer relay, said control means to operate said primary operating means to direct said wiper onto a level of said bank contacts, means whereby said control means is actuated by the first series of impulses, means for releasing said transfer relay, means whereby said last means is controlled by the primary operating means of said switch upon the termination of said first series of impulses, means for transferring the control of said control means from the operation of said primary operating means to the operation of said secondary operating means, means whereby said last means is controlled by the release of said transfer relay, said control means to operate said secondary operating means to direct said wiper onto the first bank contact of a group of said bank contacts, means whereby said control means is actuated by the second series of received impulses, a series relay, means for operating said series relay, means whereby said last means is operated by the second series of received impulses, means for releasing said series relay, means whereby said last means is operated in response to termination of said second series of received impulses, a ring cut-off relay, means for operating said ring cut-off relay, means whereby said last means is controlled by the operation of said series relay, means for preparing said test relay operating circuit, means whereby said last means is controlled by the operation of said ring cut-off relay, other means for further preparing said test relay operating circuit, means whereby said other means is controlled by the release of said series relay, said control means to complete said test relay operating circuit to cause operation of said test relay, means whereby said control means is thereafter actuated by the first impulse of a third series of received impulses, means including means for re-operating said transfer relay for transferring the control of said control means from the operation of said test relay to the reoperation of said secondary operating means,

means whereby said last means is controlled by the operation of said test relay, means to step said wiper onto the next bank contact in case said test relay remains operated, means whereby said' last means is controlled by said control means operated by the remaining impulses of said third series of impulses, other means for completing said test circuit for maintaining said test relay operated if said wiper is resting upon a busy contact and for releasing said test relay if said wiper is resting upon an idle bank contact, means whereby said last means is controlled by the release of'said test relay, other means for completing said switching relay operating circuit in case said contact has an idle potential connected thereto, means whereby said other means is controlled by the re-operation of said transfer relay, locking means for maintaining said switching relay operated independent of further action of said test relay and said transfer relay, means whereby said locking means is controlled by the operation of said switching relay, means for further disabling the control of said'control means to prevent re-operating said secondary operating means, and means whereby said last means is controlled by the operation of said switching relay.

12. In an automatic switch, a plurality of bank contacts arranged in levels and in groups, said contacts when idle having one potential connected thereto and when busy having a difierent potential connected thereto, a test relay, a test circuit including a wiper for connecting said test relay to said bank contacts, a circuit over which said switch is seized and over which impulses corresponding to a plurality of digits are received for operating said switch, means for stepping said wiper to select a level of contacts, means whereby said last means is operated by the first series of received digital impulses, other means for stepping said wiper to select the first contact of said group of contacts, means whereby said last means is operated by the second series of received series of digital impulses, an operating circuit for said test relay, means for preparing said operating circuit, means whereby said last means is operated after the selection of said first contact of said groups of contacts, means for completing said operating circuit, means whereby said last means is operated by the first impulse of a third series of received impulses, means for completing said test circuit to maintain said test relay operated if said wiper is resting upon a contact having a busy potential connected thereto and for releasing said test relay if said wiper is resting upon a contact having an idle potential connected thereto, means whereby said last means is controlled by the operation of said test relay, other means for stepping said wiper onto the next bank contacts of said group of contacts in response to the remaining impulses of said third series of impulses, means whereby said other means is controlled by the said test relay remaining operated, a busy tone circuit, means for preparing said busy tone circuit, means whereby slfiSfi means-i z xa mlled b oa hs peration :05; v1: ondaryuloperatingkq means;rimeans ;whereby-'-.=-s'a,idu=

last meoansrislcontrolled by;said test relaypmeans; for sompl ting :zsaid .1anotherzicircuitgtozoperate" said 1,secondaryggoperatinggimeans, "and .zmeansa r. whergbysaid last meansgisnperated by: said. 0011-. 1;

the wi na 0.11 of; ai h rd:1se11es10$ QC iYQd;-' trol A'me ns pin responseq-tm the subsequent.'ima pulse 3- Ina 1 ut m ic swi chuhavins mfincom ing im i QY 21 hi0h\:- thQ swi ch isis z an.. J

a ndarx;lopfi atin zm ans; the swi h; 1& test rsl m fire mtr sf rmean i flcon rolsm an ns: ton Q e a ing: m con rol; meansnm nsv ebwa dzlast means smner te z yyreceiyed impul fii oy espon insu op zp u ality. of"; digits e ns 01"; o ati ai i m mmeansimst p the wi h m t pnimary-m veme and ,foon re-ov p n ssi t a sofe qmg ns,mfi nsbwhereby sa d; last means: is controlled; by the operation;.;o f-sa id re1ay contrgl m gans .mean including;;a,;ci;rcuit for 20: op atms id o a m o1st ho witch; 5. '1.

in z on ammov e t inir p nseio the imw f: a se ond di im nszwh rebyisaid l t i lude mea, on ro1 edhv he ope ation iQ rt i trans means-i n'ope tin c c for: s i tes :25

v ean ior preparingisaid 9pe an Qircuit-; n aw by: sa m ans-- sops a ed by; I the impulses; during -the segondary movement pulses gfigsaid thirdndigitgi': p.

14. Inan'automatic;switch-such. as claimed'in h cl imizlay-imwhichi said :means operated; during; zz h h mpu s s-am r q hiedm p imary 81 11310 h es ndanmmovement;fox prep rin h test r l wop r ting circuit': includes; a;-.',series::,re1ay in; .cirocuit.w-it:h-.-tahesecondary/operating 7 1 means;;moans; for partially-preparing. saidz test relay operating circuit, means wherebynsaidglast 4 15: 1 6 11 5 45 controlled by the operation: of said series-relayxzmeans for further. preparing Saddam test .rg layncircuihiand means;wherebyasaidlast 1 means-is -control'led:byo-the releaseaof said-series MORRISv gGRIE-FKNS-g 11' References citedyin Ethe' file of :this patent:

I UNITED STATES PATENTS mban 

